Just to make sure I fully understand what you are trying to do, you have a network already formed and you want to change all the network to a different PAN ID and also modify the TX Power Level and RF Channel with the network formed?

Sorry for the late reply, there are APIs to change TX PWR using calls to the NIB attributes or directly to the PHY and the Network Update command can be used to distribute and set a new channel for the whole network. You could use Dual PAN to be part of 2 networks and switch between 2 PANs but it’s not expected in Zigbee to change the PANID and try to communicate to another network on the fly, that’d require you to leave a network and join the other network because of the network configuration and security of each network.